High-tension device



Oct. 19 1926.

1,603,603 w. H. T. HOLDEN HIGH TENSION DEVICE Filed Jan. 2, 1922 FIGA-INVENTOR WILLIAM H.T.HOLDE N ATTORNEY Patented Oct. 19, 1926.

UNITED STATES PATENT OFFICE.

WILLIAM HENRY TOWNE HOLDEN, OF NEW YORK, N. Y., ASSIGNOR TO WESTING- IHOUSE LAMP COMPANY, A CORPORATION OF PENNSYLVANIA.

HIGH-{PENSION DEVICE.

lines of force of the electrical field are pre vented from passingthrough the walls of the envelope.

Another object of my invention is to provide a device of the characterindicated in which flare-backs, corona and flash-over are obviated.

Other objects will be apparent from a reading of the followingdescription.

Heretofore in the construction of hightension tubes, particularly thoseemploying hot cathodes, such as X-ray tubes and rectifiers, no provisionwas made for preventing the lines of force of the electrical fieldsurrounding the electrodes within the envelopes of such devices frompassing through the walls thereof. Apparently, because of the passage ofthe lines of force through a dielectric body at an angle other than 90and of the concentration of such lines of force when effecting suchpassage, and, furthermore, because of the surging of these lines backand forth under the influence of an alternating current, the dielectricis sub jected to stresses which, when the dielectric is of glass,results in the breaking-down or puncture thereof, with consequentfailure of the device. The rupture of the dielectric usually occurs nearthe seals and at the sharp angle formed at the intersection of theintermediate ortion of the tube and the tubular extensions projectingfrom oppositesides of the tube. Inasmuch as these devices are veryexpensive, it is desirable to prevent such breakage. Anotherdisadvantage which is present in X-ray and rectifier tubes, as atpresent constructed, is that occasional electrical discharges, known ascorona and flashover, occur at sharp projections and along the walls ofthe tube, especially adjacent the points where the electrodes passthrough the walls. When such discharges occur they follow. the walls ofthe tube and cause it to be unduly heated, a condition which results inthe fracture of the envelope. In addition to theforegoing-"disadvantages of high-tension tubes as heretoforeconstructed, it is I also noted that gases are liberated from theelectrodes, even after the greatest care has been exercised ineliminating such gases. This liberation of gas is the result of dis-,charges, or flare-backs, from the electrodes toward the point where theelectrodes emerge from the glass stem. Such discharges heat upthe stem,puncture it and ewoseportions of the electrodes which have not beentreated to remove the occluded gases. w

The foregoing disadvantages have been obviated by the provision ofhollow conductors about the neck portions of these devices. Theseconductors are designed to divert the lines of force representing theelectrostatic field so that they conform to the contour of the envelope,and, at the same time, remove the field from the vicinity of the sealportion of the envelope. In addition to securing the foregoingadvantages, the hollow conductors also function to prevent corona andflash-over and also assist in dissipating the heat resulting from theenergy liberated at the electrodes of the tube. By properly placing ashield within the envelope, the objectionable consequences of theflare-back discharges are obviated.

An embodiment of the invention is illustrated in the annexed drawings,in. which,

Fig. 1 is an elevational view-of a wellknown form of an X-ray tubeshowing the approximate positions of the lines of orce representing theelectrostatic field surrounding the electrodes therein;

Fig. 2 is an elevational view of the device illustrated in Fig. 1,showing the metallic cover or shield applied thereto and the alteredposition of the lines of force representing the electrostatic field;

Figs. 3 and 4 illustrate the position of the external metallic coverswith respect to bulbs having ellipsoidal and cylindrical surfaces,respectively; and

Fig. 5 shows an interior shield formed of. mesh material.

The invention comprises a pair of hollow metallic shields of conductivematerial positioned exteriorly 'of the bulb and adjacent the endsthereof at the point where the lead-in wires for the electrodes, or theelectrodes, pass through the walls, which part is usually termed theseal of the tube. These shields are conductively connected to theelectrodes, or may form parts thereof, and completely surround the same,as well as the seal portion of the tube. A surface of the shieldsintersects the surface of the ena continuation of the angular surface ofthe outer shield. The inner shield is preferably made of open-meshmaterial in order to facilitate its being positioned within the tube. I

Referring now to the drawings, and particularly to Fig. 1, aconventional X-ray tube is illustrated as composed of an envelo e madeof a transparent material, such as g ass, havin an intermediate portionor lass bulb 6 an a pair of oppositely extendmg tubular portions 7,usually termed the neck portions of the tube. The contour of theenvelope varies, but usually the curvature of the intermediate portion 6is spherical, as in Fig. 2, although this section may have anellipsoidal form 8 or a cylindrical form 9, such as illustrated in Figs.3 and 4, respectively. Within the neck portions of the device aremounted, in any desired man-v ner, the lead-in wires 11, which may beconnected to the electrodes 12 or form a part thereof. High, potentialsare impressed upon the electrodes during the operation of the device.

In the devices heretofore constructed, due to the sharp curve 13 at thejuncture of the intermediate portion and the neck portion of the tube,the lines of force representing the field surrounding the electrodespass through the walls of the envelope at an angle other than 90. InFig. l isillustrated a conventional form of X-ray tube showingapproximately the arrangement of the lines of force representing theelectrostatic field- It will be apparent from this view that these linesof force enter the walls of the envelope at an acute angle and'inpassing there through are somewhat concentrated, particularly at thejuncture point previously mentioned. Because of this concentration, andthe angular passage of the force line through the envelope, togetherwith the constant surging of these lines back and forth under the actionof the alternating current, the dielectric substance is subjected toconsiderable stresses. These stresses cause the dielectric material tobecome strained and eventually cause its dissociation, with resultantbreakage of the device, particularly at the neck portions.

In order to overcome or prevent such breakage, I propose to remove theelectrostatic field from the region of the neck portion of the device bythe provision of a neck portions of the device.

pair of properly formed and proportioned ollow conductors about thatsection of the device. In Fig. 2, a pair of shields 14., formed of asuitable conductive material, which, at the same time, will also serveto radiate the heat readily, are placed in a concentric position aboutthe seal portions of the tube. Preferabl the shields are in the form ofhollow shel s which are adapted to coinpletel enclose, and be spacedfrom the The shells may have their rear portions 15 connected to theelectrodes while their forward walls 16 are arranged at an angle ofapproximately 90 with respect to the surface of the intermediate portionor bulb of the envelope. This angular arrangement is essential becauseofthe contour of the electrostatic field which it is desired to secure,since the lines of force emanate at an angle of 90 from the surface ofthe charged body and gradually curve toward the body of differentpotential. lrVhere the contour of the tube is different from thatillustrated in Figs. 1 and 2 and is such as shown in 3 and 4,-the rightangular arrangement of the surface of the walls 16' will still obtain.The. conductive shields may be secured in any desired'manner to theelectrodes, and, Where the tube employs a radiator 17 (Fig. 1) one oftheshields may be fastened thereto. It is to be appreciated that theseshields, being relatively large, also assist in dissipating the heatresulting from the energy li the electrodes of the tube.

By completely enveloping the neck portions of the tube, theelectrostatic discharges known as corona and flash-over, are prevented.This results from the well-known property of a hollow conductor, inwhich electrostatic fields cannot exist but are confined wholly to theexterior thereof.

To aid in flexing the lines of force to lie in lines substantiallyparallel to the walls of the envelope, the portion of the electrodesdisposed within the tube may be provided with a pair of conductingmembers which are preferably formed of mesh material. These conductorsare affixed to, or supported by, the electrodes or lead-in wires, or'inany other convenient manner, but should be in conductive relationshipwith the source of potential. These interior shields may form parts ofthe electrodes, or the electrodes mav be so designed as to produce thedesired effect. A portion of the surface of each of the interior shieldsis preferably arranged at an angle of 90 to the surface of theintermediate portions of the tube and should also form a continuation ofthe correspondingly arranged angular surface of the exterior shield. 7

It is obvious that these interior shields 18 may be formed of solidmaterial, but it is preferable to construct them of wire mate erated atrial, such as indicated in Fig. 5, wherein a plurality of fine wires 19ma be fastened to collars 21 and clamped to tie electrode 12. The endsof the wires are held in spaced relationship by rings or loops 22, whichmay be secured in place after insertion of the shield within theenvelope. Whether the interior shields are formed of solid or meshmaterial, the occluded gases should be treated out before or after theyare placed within the envelope.

In practice, it may be preferable to omit the interior shields (seeFigs. 3 and 4), in which event only the lines of force exterior-1y ofthe envelope will be made to conform to the contour thereof. Inasmuch asthe hollow conductors prevent any field being formed within the sealportion of thedevice, it is obvious that such lines will not be presventanywhere within the interior of the en'- velope embraced by the hollow"exterior shields. As these shields extend to a point adjacent the innerends of the electrodes, the lines of force emanating from the electrodeswill be confined to the intermediate portion of the device and thus beremoved from that section of the device where the breakage ordinarilyoccurs.

With the shields arranged as indicated in Fig. 2, the lines of forcerepresenting the electrical field will be caused approximately toparallel the walls of the intermediate pore tions of the tube. In thisway, the passage of the high potential through the dielectric formingthe envelope of the tube is prevented and the breakage or puncturing ofthe tube obviated. At the same time, the electrical. field isremovedfrom the neck portion of the envelope and the phenomena known as coronaand flash-over obviated. The interior shields assist in conforming thelines of force to the walls of the envelope and also prevent flare-backdischarges occurring within the tube as, obviously, the discharges, ifany, will strike the shield and thus be prevented from attacking thestems.

Many modifications may suggest themselves to those skilled in the art,but such as come within the scope of the appended claims may beconsidered as part of my invention.

What is claimed is:

1. The combination with two conducting members of unlike electricalpotentials disposed within a closed envelope, of means for preventingthe lines of force representing the electrical field from passingthrough the major portion of the walls of said envelope.

2. The combination with two conducting members of unlike electricalpotentials disposed within a closed envelope, of means exteriorly ofsaid envelope for preventin the lines of force representing theelectrica field surrounding said members from passrounding ing throughthe major portion of the walls of said envelope.

3. The combination with two conducting members of unlike electricalpotentials disposed within a closed envelope, of cooperatlng means oneach end of said envelope ex-' teriorly thereof for preventing the linesof force representing the electrical field stirsaid members velope. v

4. The combination withtwo conducting members of unlikeelectricalgpotentials disposed within a closed envelope, of means oneach side of said envelope and in contact with said members for causingthe lines of force representing the electrical field surrounding saidmembers to substantially conform to the contour of said envelope.

5. The combination with two conductive members of unlike electricalpotentials disposed within a closed container having in-' crating witheach other to prevent the lines of 'force representing the electricfield from passing through the walls of the envelope.

7. The combination with two conducting members operable at differentpotentials disposed within a closed envelope, of a phi",- rality ofhollow conductors of greater di ameter than the envelope connected tosaid conducting members, said hollow conductors enclosing saidconducting members and disposed exteriorly of said envelope, wherebycorona and flash-overs from those portions of the envelope Within saidconductor are obviated.

8. The combination with two conducting members operable at differentpotentials disposed within a closed envelope, of a plurality of hollowconductors of greater diameter than the envelope connected to saidconducting members, at least one of said hollow conductors enclosingthat portion offrom passing through a portion of the walls of said enmeans for preventin the lines of force representing the electrlcal fieldfrom passing through the walls of a portion of said tube comprising apair of hollow conductors asopposed and arranged approximately at rightangles to the surface of the envelope.

'11. A discharge device comprising an en: velope having a pair ofelectrodes therein and a conductor associated with each,of saidelectrodes having a portion of its surface arranged substantially at anangle of 90 to the surface of the envelope to cause the lines of forcerepresenting the electrical field to assume a position substantiallyparallel to i the walls of the envelope.

at least a 12. An X-ray device comprising an evacuated envelope 8. pairof spaced-apart electrodes of unlike electrical potentials, a pair ofhollow conical conductingshields concentric to each electrode andconnected thereto and a pair of hollow conductive shields exterior tosaid tube and enclosing and connected to said electrodes, said shieldshaving ortion thereof disposed at right angles to t e walls of saidtube.

13. An X-ray device comprising an evacuated envelope, a air ofspaced-apart electrodes of unlike e ectrical potentials, a pair ofconductive shields within said envelope, said shields being connected tosaid electrodes and having at least a portion thereof disposed at rightangles to said envelope.

14. An X-ray dev1ce comprising an evacuated envelope, a pair ofspaced-apart electrodes of unlike electrical potentials, a pair ofshields composed of wire disposed within said envelope, said shieldsbeing connected to said electrodes and having at least a portion thereofdisposed at right angles to said 15. In a hot-cathode device, meansdisposed about the neck portions thereof and spaced therefrom forremoving the electrical field from that ortion of the device.

16. A hot-cat ode device comprising a sealed envelope having a sphericalintermediate portion and oppositely extending tubular portions, anelectrode sealed in each tubular portion and projecting within said inface area disposed exteriorly of said envelope in electrical connectionwith said conducting members and enclosing the same so that heatresulting from the ener y liberated at the electrodes of the tube may bedissipated and the electrostatic field removed from a position adjacentsaid conducting members.

18. The combination with two conducting members of unlike electricalpotentials disposed within a closed envelope, of a pair of hollowshields surrounding and com letely enclosing the ends of said envelope ajacent said electrodes, each of said shields being of large surface areaand having at least a portion thereof arranged at right angles to saidenvelope so that the lines of force representing the electric field willbe made to conform to the contour of said envelope and the heatgenerated will be dissipated.

19. An X-ray device comprising an evacuated envelope composed of two oposed tubular neck portions and an interme iate portion of uniformcontour connecting said neck portions, a pair of spaced-apart electrodesoperable at unlike electric potentials within said tubular portions .andhaving their free extremities within said intermediate portion, and ahollow shield spaced from said neck portion and concentrically arrangedwith respect to each of said' electrodes adjacent the extremitiesthereof and connected thereto.

20. An X-ray device comprising an evacuated envelope composed of a bulband oppositely extending arms connected thereto, a plurality ofelectrodes, one of which is sealed within each arm and has its extremitywithin said bulb, a plurality of spaced-apart hollow conductive shieldscompletely enclosing said arms and connected to said electrodes, ahollow shield concentrically disposed adjacent the inner end of each ofsaid electrodes and connected thereto, each of said shields having atleast a portion thereof disposed at right angles to the surface of saidbulb.

In testimony whereof, I have hereunto subscribed my name this 30 day ofDecember, 1921.

WILLIAM HENRY TQWNE HOLDEN.

